The present invention generally relates to the operation of subterranean wells and, in a preferred embodiment thereof, more particularly relates to the restoration of production fluid into production tubing whose production fluid inlet perforations have become obstructed.
In conventional subterranean well completions the bore hole of the well is typically lined with a tubular casing structure having perforations formed therein and disposed at a subterranean formation containing a retrievable production fluid such as gas and/or oil. Production tubing, having an outer diameter less than the inner diameter of the casing, is installed within the casing and typically has a closed lower end disposed adjacent the casing perforations. Side wall perforations are formed in the lower end of the production tubing for receiving pressurized production fluid entering the casing through the casing perforations, and an annular packer structure surrounds the production tubing, above the casing and production tubing perforations, and seals off the tubing/casing annulus above the casing and tubing perforations. Pressurized production fluid entering the production tubing through its side wall perforations is flowed upwardly through the production tubing to the surface for appropriate retrieval.
At some time during the operation of the well completion the production tubing perforations may become blocked by an obstructing material, such as sand, thereby terminating or at least substantially diminishing the desired production fluid inflow through the tubing perforations. In order to restore the production of the well completion it has heretofore been a common practice to pull the entire length of production tubing out of the casing to clear the obstructed tubing perforations, or replace the perforated tubing section, and then re-install the production tubing within the casing. As is well known, this is a laborious, time-consuming and expensive task.
It can be readily be seen that it would be highly desirable to provide an improved technique for restoring production fluid flow in a well completion under these circumstances. It is accordingly an object of the present invention to provide such an improved flow restoration technique.